1. Field of the Invention
In one of its aspects, the present invention relates to a fluid treatment system. In another of its aspects, the present invention relates to a method of treating fluid.
2. Description of the Prior Art
Fluid treatment devices and systems are known. For example, U.S. Pat. Nos. 4,482,809, 4,872,980, 5,006,244 and U.S. Re. Pat. No. 36,896 (all assigned to the assignee of the present invention) all describe gravity fed fluid treatment systems which employ ultraviolet (UV) radiation to inactivate microorganisms present in the fluid.
The devices and systems described in the 809, 980 and 244 patents generally include several UV lamps each of which are mounted within sleeves extending between two support arms of the frames. The frames are immersed into the fluid to be treated which is then irradiated as required. The amount of radiation to which the fluid is exposed is determined by the proximity of the fluid to the lamps. One or more UV sensors may be employed to monitor the UV output of the lamps and the fluid level is typically controlled, to some extent, downstream of the treatment device by means of level gates or the like.
The system described in the 896 patent is a significant advance in the art in that it obviates a number of disadvantages deriving from the devices and systems 809, 980 and 244 patents. Unfortunately, the system described in the 896 patent is ideally suited for use in an open, channel-like system and is not readily adaptable to be used in a completely closed system where the flow of fluid is fed under pressure in a pipe.
Closed fluid treatment devices are known—see, for example, U.S. Pat. No. 5,504,335 (assigned to the assignee of the present invention). The 335 patent teaches a closed fluid treatment device comprising a housing for receiving a flow of fluid. The housing comprises a fluid inlet, a fluid outlet, a fluid treatment zone disposed between the fluid inlet and the fluid outlet, and at least one radiation source module disposed in the fluid treatment zone. The fluid inlet, the fluid outlet and the fluid treatment zone are in a collinear relationship with respect to one another. The at least one radiation source module comprises a radiation source sealably connected to a leg which is sealably mounted to the housing. The radiation source is disposed substantially parallel to the flow of fluid. The radiation source module is removable through an aperture provided in the housing intermediate to fluid inlet and the fluid outlet thereby obviating the need to physically remove the device for service of the radiation source.
While the closed fluid treatment device taught in the 335 patent (including the prior art device referred to in that patent) has been commercially successful to some degree, there is still room for improvement in the art.
Specifically, in many installations where it is desirable to treat large amounts of fluid (e.g., water), there is insufficient room to utilize a device such as that described in the 809, 980, 244 and 896 patents. Further, devices such as those taught in the 335 patent are constrained by the volume of fluid (e.g., water) which they can adequately treat (e.g., to subject the fluid to a radiation dose sufficient to perform the desired treatment).
Accordingly, there remains a need in the art for a fluid treatment system which combines the capacity of fluid volume treatment of the 809, 980, 244 and 896 patents while requiring a space of “foot print” not much larger than that used in the device taught by the 335 patent.